1. Field of the Invention
The present invention relates to a printer.
2. Description of the Prior Art
In a typical conventional printer, a reflection type photosensor is provided at the upstream side of a printing head. The photosensor faces a platen across paper.
A central processing unit receives an output voltage from the photosensor, and if the voltage is higher than a predetermined value, the central processing unit judges that paper exists (hereinafter referred to as "paper existence"), whereas, if the voltage is lower than the predetermined value, the central processing unit judges that no paper exists (hereinafter referred to as "paper empty").
After the trailing end of the recording paper has passed the photosensor, the photosensor comes to face the black platen, so that the output voltage from the photosensor becomes lower than the standard value. In consequence, the central processing unit judges that no paper exists, and suspends the printing operation after a predetermined period of time has passed. In addition, the central processing unit causes the recording paper to be discharged to the outside of the printer.
In the above-described printer, when recording paper having a printed portion is fed, the photosensor may face the printed portion of the recording paper. If such occurs, the central processing unit may malfunction such that even if the trailing end of the recording paper has not yet passed the photosensor, the central processing unit misjudges that no paper exists, and even during printing, it suspends the printing operation and discharges the recording paper to the outside of the printer.